1. Field of the Invention
The present invention relates to a roller for heat-treating film, cloth, paper and the like.
2. Description of the Prior Art
Conventional heating rollers such as a calendar roller, a laminating roller, a fixing roller and the like utilize a heater embedded inside a metallic pipe in order to heat the cuter pipe indirectly. However, the conventional method had a drawback in that the surface temperature of the outer pipe tended to be uneven, which was not suitable for heat-treating film and the like.
Therefore, in order to improve the uniformity of the heat distribution on the surface of the roller, a method such as circulating a heat medium (liquid and the like ) inside the pie, or a method combining the heat circulation method and an induction heating method is performed. However, the ancillary devices for performing these methods were complex, the weight of the pipe was increased, and the heating roller as a whole including the driving system became very expensive.